694 Professor Raphael Meldola [June 7, 



instead of resembling its inanimate or vegetable environment, bore an 

 external resemblance to some other species, the latter often belonging 

 to a quite different order. The association of protective and aggres- 

 sive resemblance with mimicry as all coming under the domain of 

 the Darwinian theory, was first suggested in 1861 by the late Henry 

 Walter Bates, who was soon followed and supported by Wallace and 

 Eoland Trimen, these naturalists having observed similar cases among 

 the butterflies of the Eastern tropics and South Africa respectively. 



Beginning with the extreme cases in which insects belonging to 

 different orders resembled each other, illustrations were shown in 

 which a moth (JEgeria bembeciformis) mimics a hornet (England) ; a 

 moth (Scoliomima) and a beetle (Nothopeus) mimic wasps (N. Borneo) ; 

 flies (Hyperechia) mimic bees (Xylocopa ; Mashonaland and Borneo), 

 and a remarkable case in which a bug mimics a leaf-bearing ant. The 

 groups of mimetic butterflies observed by Bates in the Amazon Valley 

 and which suggested the first scientific explanation of the phenomenon 

 were shown on the screen, the mimicry being between Pierinse 

 (Leptalis) and Heliconinse (Itlwmia, Mechanitis and Methona). The 

 departure in type on the part of the mimicking Leptalids was 

 strikingly shown by comparison with the Brazilian Leptalis nehemia 

 which retained the normal type of colour and pattern. The more 

 complex case recorded by Trimen from South Africa, in which a 

 Papilio (P. cenea) retains the normal colour and pattern in the male 

 while the female presents four different forms mimicking respectively 

 Amauris albimaculata, A. echeria, A. niavius and Danais chrysippus, 

 was also shown. 



The Batesian theory was based on the supposition, well supported 

 by evidence, that the imitated forms were more or less exempt from 

 persecution by insect enemies, by virtue of the unpleasant taste or 

 smell conferred by the acrid juices contained in them. Their gaudy 

 colouring and disregard of concealment thus brought them under the 

 category of " warning colours," aud the advantage derivable from a 

 resemblance to such species was sufficient in this case to warrant the 

 application of the theory of selection. The application of the 

 Darwinian theory by Bates carried with it the implications that the 

 imitating forms or mimics were devoid of distasteful qualities, that 

 they were fewer in individuals and that they inhabited the same 

 districts and associated with their models. As far as the theory could 

 be tested by the evidence available at the time of its promulgation 

 it appeared to furnish a satisfactory explanation of the phenomenon. 

 But facts began to accumulate — and Bates himself was among the first 

 to call attention to this point — which seemed to indicate that there 

 must be some other influence at work bringing about mimetic re- 

 semblances between the protected species themselves. In other words, 

 the Batesian theory, although applicable to such cases as the mimicry 

 between Leptalids and Heliconids, did not explain the resemblances 

 among the Heliconids themselves. (A group was shown illustrating 

 some of the resemblances between distasteful species of Ituna, Methona 



